Just a few days after Wrath of the Lich King Launched, We have the first 80’s:

Dessembrae from Eternal Corpse Council (EU-Mazrigos) was the first Death Knight to reach level 80 in the world on November 15 at 19:00 CEST !

Essay (US-Tichondrius) was the first death knight to reach level 80 in the United States a few hours later, at 10:00PM server time.

via mmo-champion